Setting up remote access via Apple Airport Extreme

Hi Everyone!

I'm having the hardest time setting up remote access to my Plex server. I currently have all my media on an old MacBook Pro (while I look for a better solution). The MacBook Pro is connected to the internet via Wifi. I have an Apple Airport Express plugged directly into the only ethernet port in my apartment.

I've tried manually forwarding the 32400 port but still no luck.

PLEASE HELP